Analysis of trace contaminants in biological samples (e.g., blood, urine, tissues, cell culture, plants and foods) and environmental samples (e.g., air, water and soil) is an important interest of government regulatory agencies, such as the U.S. Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA). Existing analytical techniques employ a variety of detection strategies, emphasizing, e.g., high pressure/performance liquid chromatography (HPLC), gas chromatography (GC), mass spectrometry (MS) and capillary electrophoresis (CE).
A general limitation of existing methods is that a diversity of procedures is required to determine a wide variety of contaminants. For example, while mass spectrometry is a very powerful analytical technique, some forms of mass spectrometry are expensive, analyte-dependent, prone to down-time, or subject to contamination. Novel MS techniques such as electrospray (ES) have emerged, but the principle application of ES-MS has been to purified proteins. Impure small molecules are quite a different challenge, especially at trace levels. Particle beam mass spectrometry is not good for polar, thermally labile compounds. Immunoassays are limited by the requirement for specific antibodies, and are susceptible to interferences.. Capillary electrophoresis is not sufficiently sensitive for some analytes because of the small injection volumes. Also quite different conditions are generally necessary for different analytes.
Imaging analysis of biological and environmental samples is also important. In this technique, at least several of the constituents, usually major ones, of the sample are detected, as by chromatography, electrophoresis or mass spectrometry. This includes methods such as amino acid analysis in which a protein is hydrolyzed into its constituent amino acids, and the latter are detected.